Catecholamines, e.g. epinephrine modulate the strength and rate of beating of the heart by stimulation of adenylate cyclase and subsequent accumulation of cAMP intracellularly. The major purpose of this research project is to understand at a molecule level the way in which the Beta-adrenergic receptor, after occupancy by catecholamines, subsequenty activates the adenylate cyclase enzyme. The specific aims of this study include: 1) To isolate Beta-adrenergic receptor binding from the adenylate cyclase activity, 2) to characterize the biochemical components and physical characteristics of the receptor and enzyme preparations, 3) to "reconstitute" a cell-free catecholamine-sensitive adenylate cyclase system from solubilized Beta-adrenergic receptors and adenylate cyclase. Although the information obtained from these studies will eventually be applied to and extended in mammalian myocardial preparations, the proposed experiments will utilize the plasma membranes from frog erythrocytes, an excellent model system for Beta-adrenergic adenylate cyclase effects. Methods have already been developed for solubilization of receptor and enzyme from the frog erythrocyte and for assay of these two activities in membrane-bound and solubilized form. A wide variety of hormones, in addition in catecholamines, elicit their effect via stimulation of adenylate cyclase and generation of cAMP. Thus, elucidation of the way in which receptor occupancy is translated to enzyme activation will be of widespread physiological significance.